I've had the ACA500Plus for about two weeks now and have had a wonderful experience with it up until a couple of days ago. I'm experiencing the exact same E5 error as described on post ACA500+ stopped working (E5)
I was simply working with my files using the stock 3.1 WB that came with the ACA when the screen suddenly went black, and the power indicator on my A500 flashed a couple of times and then went totally out. When I did a soft reset the ACA came up with the E5 error and I got the same green grid on a black background on my monitor. When I did a complete power down/up I received the same error/screen. This went on several times.
When I removed the ACA the system booted up fine with my old WB 1.3 floppy and I've been able to boot up that way since. I have a non-modified A500 with a rev 5 motherboard and a Supra Card 512k trapdoor memory expansion (I tried removing that and the re-installed the ACA but unfortunately the E5 error came back). I cleaned the contacts on the A500 and the ACA with no luck. By the way, I have your RTC module installed on the ACA and I tried booting with it installed and not installed. I've never installed the ACA upside down either.
What is a E5 error and what do I need to do to get it fixed? I really got to love the ACA500Plus in the short time that I had it working and would really love to get it back. My order number is 55937
Thanks for all you do!